|COSTA-HURTADO, MAR - Orise Fellow|
|DEJESUS, ERIC - Orise Fellow|
Submitted to: International Poultry Scientific Forum
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/2015
Publication Date: N/A
Technical Abstract: Domestic ducks and geese are common backyard poultry in many countries, frequently in contact with wild waterfowl, which are natural reservoirs of avian influenza viruses and have played a key role in the spread of Asian-lineage H5N1 highly pathogenic avian influenza (HPAI). In late 2014, a reassortant H5N8 clade 18.104.22.168 HPAI virus spread by migratory birds into Europe and North America, and mixed with North American low pathogenicity AI viruses to produce an H5N2 HPAI virus. These viruses spread through the United States causing outbreaks in poultry in 2015. To evaluate the infectivity, transmissibility, and pathogenicity of these H5 HPAI viruses in domestic waterfowl, two-week-old Pekin ducks and Chinese geese were inoculated with the two index viruses: A/Northern Pintail/Washington/40964/2014 H5N2 and A/Gyrfalcon/Washington/40188-6/2014 H5N8. Oropharyngeal and cloacal swabs were collected from inoculated and contact birds at 2, 4, 7, and 10-11 days post-inoculation (dpi) to determine virus shedding. None of the inoculated or contact Pekin ducks showed clinical signs, but a few of the geese presented neurological signs and died. Pekin ducks also shed lower titers of viruses and for a shorter period of time than the geese. Pekin ducks became infected and transmitted the viruses to contacts when inoculated with high virus doses: 10^4 and 10^6 mean embryo infective dose (EID50), but not with a lower dose (10^2 EID50). All geese inoculated with H5N8 HPAI virus became infected and transmitted the virus to contacts regardless of the inoculation dose. Only geese inoculated with the higher doses of H5N2 HPAI virus and their contact birds became infected, indicating differences between the two index viruses. The peak of virus shedding for both viruses, in geese and ducks, was at 4 days post inoculation (dpi). In conclusion, the novel HPAIV H5 viruses can infect domestic waterfowl and easily transmit to contact birds, with geese being more susceptible to infection than ducks. The disease is mostly asymptomatic, but infected birds shed virus for several days, representing a risk to other poultry species.